Automatic fan heater



Oct. 2, 1956 J. P. THEISEN 2,765,393

AUTOMATIC FAN HEATER Filed March 29, 1954 3 Sheets-Sheet 1 w NH | I I II I .3 I 1 INVE NTOR.

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AUTOMATIC FAN HEATER Filed March 29, 1954 Z 0Q i i- 3 Sheets-Sheet 3 J67:8 I 7,- 70a 70 fa United States Patent AUTOMATIC FAN HEATER John P.Theisen, Jacksonville, Ill., assignor, by mesne assignments, to New YorkShipbuilding Corporation, a corporation ofNew York Application March 29,1954, Serial No. 419,274

4 Claims. (Cl. 219-39) This invention relates generally to electricspace heaters and more particularly to a heater which will serveeffectively both as a source of radiant heat and a circulating means.Specifically, the invention may be termed a combination heater and fanassembly having improved fea tures of design and construction whichbring about improvements in functional results and operation.

It heretofore has been a practice in the art to provide combinationcirculating fans and electrical heater elements in which air iscirculated over electrical resistance heaters. However, by and large,all such previous combination fan and heater assemblies have utilizedmeans for the assembly which cause axial .flow of air through theassembly, that is, from front to back through the fan and housing.

.It is one of the basic intentions of this invention to provide a newimproved heater and fan combination in which the housing thereof isarranged to permit a reentrant recirculation of air through an annulusor cham ber located peripherally outward of the central heating chamberto give improved operating characteristics and efficiency to an assemblyof this character. Specifically, this basic intention of .my inventionis carried out by providing a double shell construction in which theshells are separated by an air space. The inner shell is open ended andthe outer shell encloses the rearward portions of the housing such thatre-circulation of air takes place by drawing air inwardly from thefrontal portions of the housing for discharge centrally of such frontalhousing portion. This particular type of air flow is thought to havespecial advantage in providing a central core of heated air forcedoutwardly from the housing by a circulating fan, which is substantiallyuniform in its intensity across the entire frontal area of the device.Coupled with the advantages to be found in the improved housing portionof my assembly are improved control means which provide variable fanspeed and heat intensities. Thermostatic means are also coupled in theassembly to provide a new and improved safety means for controlling theoperation of heater elements and which is substantially responsive toambient temperatures of the space or room in which the heater-fan islocated and operated. Further means are embodied in the assembly forproviding universal tilting adjustment of the housing for the fan andheater elements such that a versatile device is produced capable of awide variety of operatingpositions.

The main object of this invention .is to provide a new and improvedcombination heater and fan assembly having intake and discharge passageson the same side of its housing whereby there is a reentrant air flowthrough the device.

Another object of this invention is to provide a new 2,765,393 FatentedOct. 2, 1956 and improved combination heater and fan having a novelhousing construction whereby the outer wall portions thereof areeffectively insulated by an air passage designed to accommodate the flowof intake air for the fan.

Still another object of this invention is to provide anew and improvedcombination heater and fan assembly in which a thermostatic member isemployed to provide a convenient climatizing control and an improvedsafety mechanism for preventing overheating of the device.

The above and further objects, features and advantages of this inventionwill become apparent to those familiar with the art from the followingdetailed description and specifications therefor, and with particularregard to the illustration of a preferred embodiment of its concepts asfound in the accompanying drawings hereof.

In the drawings:

Figure 1 is a front elevational view of an improved heater-fancombination embodying the concepts of this invention and illustratingthe general features and structural arrangements of the improvedassembly thereof;

Figure 2 is a top plan view of the device illustrated in Figure 1;

Figure 3 is a side elevational view with parts thereof broken away incross section at substantially line 3-3 of Figure l to illustrate thearrangement of elements and working mechanisms disposed within theinterior of the housing whereby I am able to carry out the intents andpurposes of this invention;

Figure 4 is a schematic wiring diagram showing the electricalarrangements and systems employed in my improved combination heater-fanassembly;

Figure 5 is an enlarged side elevational view of an improved control andoperating switch mechanism embodied in my device;

Figure 6 is anend elevational view of the control switch mechanism foundin Figure 5;

Figure 7 is a top plan view of the control device shown in Figures 5 and6 but enlarged thereover; such illustrating in particular thethermotatic control elements e.. bodied therewith; the view being takensubstantially from vantage line 7-7 of Figure 5 and Figure 8 is across-sectional view of the control switch illustrated in Figure v5taken substantially at line 8-5 of Figure 5;

Figure 9 is a partial cross sectional View of the cam actuator of theswitch means shown in Figure 5, taken at line 99 of Figure 5; and

Figure 10 is a cross sectional showing, similar to Figure 9, taken atline 10-10 of Figure 5.

The embodiment of this invention as illustrated in Figures 1 through 3of the drawings includes a standard or support member 20, having twosubstantially U-..hapcd divergent leg portions 21, 21, each carryingrubber foot pads 22, 22 adjacent opposite ends of a lower platformportion 23 thereof. Pivot bearing housings 2d are formed at the juncturepoints of the two leg portions, or that is at opposite upper ends of thestandard; such bearing -housings being coaXially aligned. The standard24? connects directly to and pivotally supports a substantiallyfrustroconical shaped outer shell member 26 of the fan housing. Shellmember 26 carries on opposite sides and at positions located justslightly below its horizontal diametrical center line, a pair oftrunnion 'post members 27, 27 which are pivotally housed in the twopivot housing members 24 of the bracket standard 20.

From Figure 2 in particular it will be recognized that tne outer housingshell 26 is enclosed on its rearward side by a conical shaped rearwardwall portion 28, and that the front side thereof (see Figure 3) is openexcept at its outer periphery where the same is rolled inwardly toformulate a lip portion 29 of annular configuration.

Supported concentrically inward and coaxially of the outer shell is aninner shell member 30, formed as a substantially open-ended cylinder,which is attached to and supported by the outer shell by means ofintermediate-1y extending and radially disposed Web arm members 3f, theoutermost radial ends of which are conveniently riveted or fastenedrigidly to the lip member 29 of the outer shell and the innermost endsof which are riveted or rigidly fastened to the exterior side walls ofthe inner. shell; rivet members 32 being utilized for this purpose inthe particular embodiment illustrated.

With further regard to the inner shell 30, it will be noticed that thesame carries a grid plate 33 transversely thereacross adjacent itsforward or front end; such grid plate being formed with a plurality ofair passage apertures or as a screen member. A decorative hub andsupporting member 34 is disposed substantially diametrically across theforward end of the inner shell, outwardly of the screen grid 33. Sincethe screen grid 33 is placed slightly inwardly from the leading edge ofthe inner shell the latter member is rolled inwardly as at 35 to assistirl promoting the decor of the frontal aspects of the housing and toperform the function of hiding the fastening of the grid member 33 tothe inner shell member, as by rivet means 36. It will further beregarded that while the nner and outer shells are aligned concentricallyor coaxrally, the inner shell extends forwardly of the forward lip oredge of the outer shell so that the Web arms 31 connect to thecylindrical wall of the inner shell at positions substantially midwaybetween its front and back edges. (See Figure 3.)

The concentric arrangement of the inner and outer shells provides orforms an inner space or chamber of annular configuration, labelledgenerally by number 38 located intermediate the opposed wall faces ofthe two described shell mcmbers, or that is, between the two shellmembers. As stated heretofore, the rearward wall 28 of the outer shellis substantially uninterrupted by openings. However. a slotted portionor aperture 39 is provided adjacent the unoer end thereof which permitsthe accessible proiection of a control knob 40 for a combination controswitch means 41 which will be described more fully hereinafter. Locatedimmediately beneath the control knob 4th of the switch assembly is ahandle member 42 joined to the re rward wall 28 of the other shell; thislatter member being for the convenience of tilting the housing assemblyabout the pivots or trunnions formed at the junction points of the outershell with the standard member 20.

Within the outer shell 26 and immediately behind the inner shell 3% is aswitch sup orting baffle plate means 43 disposed in substantialparallelism to the rearward wall 23 of the outer shell and locatedgenerally at the upper end of the device as shown in Figure 3. Suchbaffle wall 43 has a lower platform portion 44 on which the switchassembly 41 is supported. A secondary bafile extension 45 is joined tothe balfle wall 4-3 adjacent the latform portion 44 thereof. Locateddirectly behind the baffie wall extension 45 is an electric indicatorlamp means 46, and mounted beneath such lamp and substantially coaxiallyof the inner and outer shell members is an electric fan motor means 47having the usual armature shaft for supporting a conventional fan blademeans 43. Motor 47 is supported on a bracket means 49 which in turn iscarried at its lower end by an annular bafile ring 50 radiallysurrounding the fan blade means 48 concentrically inward of the innershell 30. A plurality of combination bracket and heating element holdermeans 51 serve to join the concentric baflle ring'50 coaxially of theinner shell 30 and support two substantially annular heating coils 52and 53, best shown in Figure 4.

With regard to the heater elements and combination holding means 51therefor, it will be recognized that the same are located intermediatethe annular baffle ring member and the inside wall of the inner shell30, that is, within a second annular space formed by the concentricinterpositioning of such housing portions.

The above described elements and arrangement comprise the majormechanisms and portions which, when assembled in the manner illustrated,go to make up the improved combination heater and fan assembly of thisinvention. However, particular advantage and merit is to be found in thenew and improved combination control switch means or assembly 41 whichwill now be described in greater detail and which is illustratedspecifically in Figures 5 through 10 of the drawings.

The switch assembly 41 comprises a switch block 54 of Bakelite or othersuitable insulating material which is shaped substantially as ahorseshoe or that is, U-shaped. for the rotatable reception or mountingof a barrel switch cam member 55 mounted on a rotatable thermostat andswitch actuating shaft member 56. The assembly also includes athermostatic means, indicated generally by numeral 57 and a plurality ofleaf spring switch-arms or blades 58, 59 and 60.

Specifically the switch block 54 carries the switch arms 586ll along oneside thereof, so that the same bridge or extend across the centralopening of the block in which the rotatable cam member 55 is housed.Such switch arms or blades, are rigidly held at one end as by screwmeans 61 to one upright arm portion of the U-shaped switch block leavingthe other end thereof free for flexing movement toward and away fromcontact members 62, 62a and 62]) carried on the other arm of block 54,such as contact 62 illustrated in Figure 8 in particular. It will benoted that each of such contact members is associated with a terminalconnector 63 of electrical conductive material. Further, each of theswitch blades is adapted at one end adjacent the connective screws 61,for connection with electrical supply conductors and the like. suchadaptation taking the form of terminal connectors 64.

The combination thermostat and switch actuating shaft 56 is rotatablysupported on a lower wall portion 65 of the switch block and a bracketmeans 66 is utilized directly beneath the operating knob 40 forsupporting the shaft. The cam member 55, as will be recognized presentlyfrom Figures 8, 9 and 10, is supported on shaft 56 for rotationtherewith, and such comprises an insulating member having three camlobes or portions which are staggered in arcuate disposition as at 68,69, and 7 9. Lobe is common to all three of the cam lobe portions andextends the full vertical height of the cam member. Portion 68 islocated adjacent the upper end of the cam member and portion 69 islocated at a level lower or beneath the level of cam portion 68. Suchtwo cam portions 68 and 69 are so related to one another in vertical disosition that the same individually actuate switch blades 58 and 59respectively, While cam portion 70 initiates all three of the switchblades simultaneously. Cam portion 68 comprises substantially a fullannular surface with the exception of a cut-out portion 71 which liesover cam por tion 69 and extends to cam portion 70. When the barrel cammember is rotated such as to bring the peripheral or outside edge of camportion 68 into engagement with the leaf switch blade 58, the latter isbiased outwardly from its corresponding contact 62 which is carried onthe switch block. This serves to open circuit between a contact 73carried by switch blade 58 and opposed contact 62 on the switch block.Likewise, when cam portion 69 is brought into position so that itcontacts the intermediate switch plate 59, circuit is broken between thelatter member and its corresponding contact 62a carried by the switchblock. When cam portion 70 is brought rotatably to an operating positionor is in contact with all three of the switch blades, the latter aresimultaneously biased outwardly from their corresponding contacts on theswitch block to interrupt all circuits relatedthereto.

It will benoted additionally, that cam portions 69 and 70 each bear adetent projection 69a and 70a respectively, which are designed to engagewith detent depressions 72 formedin the switch blades 58-60. Such detentarrangement serves to'lock removably the rotatable cam member indesigned positions of operation for certain purposes. In greaterparticular when cam portion 70 engages all three of the switch bladesall circuits through the switch assembly are broken and the detent means70a removably holds this condition by engaging depressions 72 of theswitch blades. Also while the cam surface 68 engages switch blade 58,the remaining two switch blades 59 and 60 will be in circuit closingcontact with their contacts 62a and 62b on the switch block, while blade58 will be biased to a position as illustrated in Figure 8, whereatcircuit therethrough is interrupted. When cam ortion 69 is in operatingengagement with switch blade 59, circuit therethrough is open andcircuits through blades 58 and 60 closed. Other combinations andarrangements of the switch cam means .may be readily adapted for thepurposes illustrated, but for present purposes the arrangement shown anddescribed hereinabove, willmeet the conditions and requirements of theseveral circuits and controls necessary to carry out the intents andpurposes of my invention. Of further consequence 'in the operation ofthe switch cam, is the space or gap left intermediate cam detentportions 6% and the leading edge or corner 74 of the cam surface 68.When the .gap portion of the cam is opposite the switch blades 58, 59and 60, all three of the latter have their respective contacts 73, 73aand 73b in engaging position with the respectively associated contacts62, 62a and 62b so that all circuits through the switch means areenergized.

In addition to the several switching means hereinabove described, theswitch assembly 41 includes the thermostatic assembly 57 which will .nowbe described. It will be understood from an examination of Figures 5, 6and 7, in particular, that the switch block 54 has a fixed ear bracketportion 75 carrying a laterally extending bi-metal arm member 76supporting an adjustment collar and screw means 77 at its outermost end.Such screw means is adapted to bear against a resilient leaf 78 carryinga contact member 79 and which in turn is mounted in cantilever fashionon an insulating block assembly 80. Block 80 also includes a terminalconnector means 81 which is connected with the resilient switch blade78. The block assembly 84) includes additionally, a secondary switch arm82 carrying a contact member-83, the latter of which is disposedopposite contact 79 of theresilient blade 78.

The entire block assembly is supported on a bracket means 84 which ispivotally connected 'by pin '85 to the switch block bracket 75. Bracket84 is formed with a vertical or upright wall portion 86 which serves toact as a bearing surface for an eccentric 87 carried for rotation withshaft means 56. A leaf spring 88 is joined to the block assembly 88 andwall portion '86, as by bolt or screw means 89; such leaf spring bearingagainst the shaft means 56, but on the opposite side thereof from wallportion 86 of the bracket means 84. As the shaft 56 is rotated, theeccentric 87 causes the entire switch assembly including bracket 84,secondary contact arm 82 and resilient blade 78 to pivot about the axisdefined by pivot means 85. Thus, simple variations in the tension orbias of the switch blade 78 relative to contact 83 of the secondaryswitch arm 82 are accomplished by pivotally moving the switch assemblyrelative to the end of adjustment screw means 77. Stated in other words,the normal bias or operating characteristic of the switch blade 78 isset at initial installation by adjusting the axial extent of the screwmeans 77 beyond bi-metal arm 76, thereby to tension the blade 78 andregulate its action toward and away from the secondary switch arm '82under certain thermal conditions. Thus as the eccentric 87 is rotatedwith shaft 56, the switch assembly (i. e., resilient blade '78 and arm82) is gradually moved away from the adjusting screw 77. This makes 'itnecessary for the bi-metal blade 76 to travel further in order to havescrew 77 bear against resilient blade 78 to thereby separate the contact79 from the contact 83.

Return movement of the thermostatic assembly to the position illustratedin Figure 7 is accomplished by and large through the medium of thespring means 88 which engages the shaft 56 in a manner to urge theswitch assembly to follow the eccentric during rotational motion ofshaft 56 and control knob 40.

Relating the thermostatic system to the control knob and the severalleaf spring switching elements controlled by cam means 55, it will beunderstood from Figure 8 that the eccentric 87 and the operation of thethermostat takes place by and large during the operation of cam surface68, or that is, throughout the arcuate extent of this cam portion. Thisin effect, permits variable control of the circuit being energized whencam surface 68 is in operating relation with its adjacent contact arm 58as will now be explained.

Referring now to Figure 4 of the drawings, wherein I have set forth aschematic layout of a typical circuit and electrical control system forthe operation of my present device, it will be recognized that theseveral switch arms 58, 59 and 60, are represented therein, inconjunction with associated contacts 62, 62a and 62b, respectively,carried by the switch block 54 as heretofore described. Switch blades 58and '59 are connected in circuit with line or supply conductor 90 byintermediate conductors 91 and 92 respectively. Switch blade 58cooperates with the contact 62 which is in circuit with conductor 93leading to the motor 47, a conductor 94 connects the motor 47 to aconductor 95 which is in circuit with contact 62b, switch arm 60 and areturn line conductor 96. Conductor 95 also is coupled to thethermostatic assembly comprising contacts 79 and 83, and the resilientswitch arm 78. A conductor 97 couples the resilient blade 78 to theindicator light 46 and conductor 98 couples light 46 to contact 62awhich cooperates with the switch blade 59. A first heater element 53 isconnected across the light 46 and joined to conductors 97 and 98. Asecond heater element 52 is arranged in series with conductor '53. Thisarrangement gives a complete circuit with the exception of a resistance99 coupled between conductors 93 and 98, between the motor 47 andcontacts 62 and 62a.

It will be recognized that as the cam member 55 is rotated clockwisefrom its off position whereat detent portion 78a is in engagement withthe detent recesses 72 of the several switch blades, cam portion 69effectively biases blade 59 outwardly from contact 620, which conditionmay be maintained by locking detent portion 6911 with recess 72 of blade59, if desired. Thus circuits through blades 58 and 68 are energized,resulting in a direct energization of the motor 47 through conductors98, 91, 93, 94, 9'5, switch blade 60 and return line concluctor 96. Thelow energization of the heating coil circuit also takes place viaconductors 9'0, 91, 93, blade 58, resistor 99, conductor 98, heatingcoils 52 and 53, conductor 97, thermoplastic switch 57, conductor 95 andthe closed switch blade 68 and return line conductor 96. Due to theresistance 99, the energization of the heating coils 52 and 53 in thisparticular operating condition is only slight, so that for all practicalpurposes the fan is on at full speed with very little or no heat beingemitted by the energization of the heater coils. This operatingcondition is best suited for and designed to accomplish circulation ofair, as for instance in the summer time.

When the cam 55 is rotated to bring the gap between corner 74 of the camsurface 68 and the detent portion 69a of cam portion 69 opposite theblades 58, 59 and 60, then all three of the circuits are energized, thatis all three of the switch blades 58, 59 and 60 are closed with theirassociated contacts 62, 62a and 6217, respectively, resulting in a highmotor speed and a high heat output.

Continued clockwise rotation of the cam member 55, however, brings thecam surface 68 thereof into engagement with switch blade 58 to bias thelatter outwardly or to break circuit therethrough. In this operatingcondition switch blades 59 and 60 will be closed so that the circuitthrough the motor 47 will include conductors 90, 92, blade 59, conductor98, resistance 99, conductors 95 and switch blade 6t and return lineconductor 96. Since the motor is energized over resistance 99 its speedis correspondingly reduced. Energization of the heating coils 52 and 53will take place directly however, with the circuit thcrethroughincluding conductors 99, 92, switch blade 5% conductor 93, coils 52 and53, conductor 97, the switch means 57, conductor Q5, closed switch blade69 and return line conductor 96. In this condition, the thermostaticmeans, will continue to maintain the circuit to the heating elementsclosed, so long as the ambient heat generated by the heating elements isnot sufficient to cause an automatic opening of the thermostaticallycontrolled switch. Since the switch blade 78 is automatically returnedto its operating condition upon cooling of the bimetal blade 76 in thiscondition of operation, the thermostat controls intermittentenergization and deenergization of the heating elements depending on theoperating characteristics of the thermostat eccentric. It will berecognized also, as related to the eccentric means 87, that as continuedrotational adjustment of the cam 55 takes place, throughout the lengthof cam portion 63, decreasing tension is placed on the resilient blade 78 as the eccentric 87 moves the switch assembly away from the adjustmentscrew 77. Thus toward the end of the cam surface 67, or that is, in thatportion adjacent gap portion 71, the

eceentrics bias of switch means 57 is greatest and a maxi mum amount ofheat will be needed to cause opening operation of the thermostaticcontrol. Thus throughout the length of cam surface 68, there is provideda means for gradually varying the heat output of the heating coils byadjusting the operating characteristic of the thermostatic control. Ofcourse, as stated heretofore, when cam portion 70 is brought oppositethe detent portions 72 of the several switch blades 58, 59 and 60, allthree of the switch blades are held away from their respective contacts62, 62a and 62b, thus, deenergizing the entire device.

With respect to the thermostatic control means, herein shown anddescribed, it is also of importance to note, that in addition to theautomatic energization and deenergization of the heating coil elementsas caused by current surges and ambient temperatures of the return airin chamber 38 especially, the thermostat also provides a unique safetyshut-off for the device. For example, if for any reason the airdischarge passageway becomes blocked over, as by the device tipping overon its face, rapid increase in the ambient temperature surrounding thethermostat will result, causing a disruption of the circuit to theheating elements etc.

It is also of importance to note that in addition to the particularposition of the heater housing illustrated, the same may be tilteduniversally about its pivotal axis as provided by its connection withthe standard means 20. Thus, great convenience and the versatility ofoperation is afforded the user.

While I have herein shown and described the elements and operatingfeatures and provisions of my invention as related to one particularform of combined heater and fan unit, it will be understood thatnumerous modifications, changes and substitutions of equivalents may beentered into therein without necessarily departing from the spirit andscope of its inventive concepts. Therefore, it is not my intention toherein be limited to the particular form of my device shown anddescribed, except as may appear in the following appended claims.

I claim:

1. In a space heater, a rotatable fan means, motorized means forrotating said fan means, an outer housing shell encasing said fan andmotorized means radially thereabout and to the rear thereof, said outershell being open at one end only forwardly of said fan means, an annularbaffle wall mounted concentrically of said Outer shell and radiallyabout said fan means, said bafile wall lying wholly within the axiallimits of said outer shell, an inner shell mounted concentricallybetween said outer shell and said battle wall to provide first andsecond annular spaces or chambers, said inner shell extending axiallyforwardly of the axial limits of said outer shell and wall, annularresistance heater means, mounted in said first chamber between saidinner shell and said bafile wall, and a combined thermostatic controlswitch means mounted adjacent said second chamber for controlling theenergization of said fan and regulating the thermal output of saidheater elements in response to ambient temperatures; the path of aircirculation of the heater being such that the intake air passes throughthe frontal wall of said heater via said second chamber across saidthermostatic means to the rear of said fan and outwardly through theinterior of said baflle wall and inner shell means.

2. In a space heater, a rotatable fan means, motorized means forrotating said fan means, a pair of concentrically related shell members,the outermost one of which encloses the rearward portions of said fanand motorized means, an annular bafiie wall positioned concentricallyinward of the innermost of said two shell members, the concentricrelationship of said shell members and wall member forming a pairofannular chambers, resistance heater coil means mounted in the radiallyinnermost of said two chambers, and a combined thermostatic controlmeans and plural circuit switch means located within said outermostshell and in communication with the air passageway formulatedintermediate the said two shell members, the arrangement of saidelements being such that the fan means serves to disperse air over saidheater coils and through the interior of said bafile and innermost shellmembers with intake air being circulated through the annular chamberformed between said two shell members and over the thermostatic means,the latter of which controls the operation of said heater coils.

3. In a space heater of the class described, a rotatable fan means,motorized means for rotating said fan, a pair of concentrically relatedshell members surrounding said fan means, the outermost one of whichencases said fan means to the rear thereof and formulates an enclosingrear wall for the heater, an annular baffle wall located concentricallyinward of the innermost of said two shell means and surrounding said fanmeans, said innermost shell and baffie wall member being open ended withthe concentric relation of said two shell members and bafile wallserving to formulate a pair of annular spaces or chambers, a resistanceheater coil means disposed within the radially innermost one of said twochambers, and said second chamber serving as an annular air passagewayfor intake air; the circulation of air by the space heater being suchthat both intake and discharge air openings are located in one wallthereof and a combined thermostatic control means mounted adjacent inthe rearmost chamber for controlling the thermal delivery of the heatercoil proportional to the ambient intake air requirement.

4. In a space heater, a rotatable fan means, motorized means forrotating said fan means, an outer housing shell encasing said fan andmotorized means radially thereabout and to the rear thereof, said outershell being open at one end only forwardly of said fan means, an annularbaffle wall mounted concentrically of said outer shell and radiallyabout said fan means, said baffle wall lying wholly within the axiallimits of said outer shell, an inner shell mounted concentricallybetween said outer shell and said baflie wall to provide first andsecond annular spaces or chambers, said inner shell extending axiallyforwardly of the axial limits of said outer shell and wall, annularresistance heater means, mounted in said first chamber between saidinner shell and said bafile wall, and a combined adjustable thermostaticcontrol switch means mounted adjacent said second chamber forcontrolling the energization of said fan and regulating the thermaloutput of said heater elements in response to ambient temperatures; thepath of air circulation of the heater being such that the intake airpasses through the frontal wall of said heater via said second chamberacross said thermostatic means to the rear of said fan 1'0 and outwardlythrough the interior of said baffle wall and inner shell means and oversaid heater means.

References Cited in the file of this patent UNITED STATES PATENTS1,926,537 Hoffman Sept. 12, 1933 1,954,872 Gilbert et al. Apr. 17, 19342,118,759 Dillman May 24, 1938 2,120,937 Kronmiller June 14, 19382,158,602 Calhoun May 16, 1939 2,583,754 Theisen Jan. 29, 1952 2,619,578Jepson et a1 Nov. 25, 1952

